On April 15, 2016, the Canadian Food Inspection Agency (CFIA) announced a food recall warning regarding the possible contamination with Hepatitis A, a viral liver disease, of the frozen fruit product, “Nature’s Touch Organic Berry Cherry Blend”. Canadians have been advised that the food recall is in effect in the provinces of Ontario, Quebec, New Brunswick, Nova Scotia, and Newfoundland and Labrador, where the product has been sold. As of April 22, 2016, there are eleven related Hepatitis A cases in three provinces (1): Ontario (8 cases), Quebec (2 cases), and Newfoundland and Labrador (1 case).
While it is frightening to know that Hepatitis A can be contracted by eating frozen berries, a product that is supposed to be healthy, coming into contact with hepatitis A can be quite easy. Hepatitis A is usually linked with the lack of potable water and inadequate sanitation, and the virus is spread mainly by the faecal-oral route. It can be acquired from any food and drinks prepared by a person who is infected, as an infected person can carry, due to improper hygiene, traces of their faeces when preparing refreshments. Shellfish derived from waters containing sewage can also carry hepatitis A. The frozen berries sold at Costco in Canada were at some point contaminated with hepatitis A from at least one infected worker (during harvest, manufacturing or processing) who was handling the berries, and who did not take preventative hygienic measures such as frequent hand-washing with soap and water, and the use of gloves. After infection with hepatitis A, symptoms usually reveal themselves two to seven weeks after viral infection. Fever, loss of appetite, abdominal pain, jaundice, dark urine, vomiting, and fatigue are all symptoms. Although cases usually last one to two weeks, a few severe cases can last several months before recovery, and some people can die from liver failure. People with pre-existing liver conditions are at a greater risk of severe illness. Older people tend to get sicker than younger people after infection.The disease is not chronic (there is usually no permanent liver damage), and lifetime immunity is acquired either from recovery after infection, or through immunization with the hepatitis A vaccine.
The hepatitis A virus, a picornavirus, is of an icosahedral shape and does not contain an envelope. It possesses a single-stranded RNA packaged in a protein capsid. There are three different numbered human genotypes of the virus, but type IA is the most commonly occurring. Genetic sequencing of the virus can reveal which molecular subtype of the virus is associated with a particular outbreak (2), thus narrowing down unassociated cases of infection. To determine whether infection has occurred, a blood test to look for IgM anti-hepatitis A antibodies, a particular immune response, can detect the virus as early as two weeks after the initial infection.
Known as a “traveller’s disease”, hepatitis A is usually associated with countries that are less developed, but it does and can occur in Canada. In industrialized countries, outbreaks of hepatitis A are often linked to contaminated produce (3). During March 2012, there was a small outbreak of hepatitis A in British Columbia, Canada that was traced to pomegranate seeds in a frozen fruit product (4). April 2013 saw more than 70 cases of hepatitis A infection in four Nordic countries (5,6). In the United States, there were 165 confirmed cases of hepatitis A infection found across 10 states, in 2013 (7). This outbreak was traced to pomegranate arils found in a frozen berry product sold at Costco, and 44% of the infected patients were hospitalized. Frozen fruit can last for up to a year in the store, and hepatitis A can incubate for up to 50 days, so a hepatitis A outbreak is often detected only after many people have been infected (8). Case-control studies, where patients with (case) and without (control) a disease, such as hepatitis A, are compared retrospectively for frequency of exposure to a risk factor (such as the contaminated frozen fruit), and through this study method the source of the outbreak can be unraveled.
Costco is publicly offering free vaccination clinics to affected individuals of this recent 2016 outbreak, as vaccination can prevent the disease symptoms from occurring if given within two weeks of exposure (9). There are two options for post-exposure prophylaxis of hepatitis A. The first is the vaccine injection, which is an inactivated version of the virus. The second is immunoglobulin (IG), which is injected and consists of antibodies which fight the virus to prevent infection. It is a blood product produced from paid donors. An exposed individual who may be allergic to the vaccine may opt for the IG. A study comparing the two options found that immunoglobulin was slightly more effective than the vaccine (10). However, the vaccine offers a lifetime immunity, whereas the response of immunoglobulin against hepatitis A is only for three months after the IG administration-subsequent exposure to hepatitis A can still result in an infection. Individuals can get a pre-exposure prophylaxis vaccination, which renders permanent immunity before any exposure, and travellers to countries where hepatitis A is endemic are required to receive the vaccination before leaving to their destination.
The recent 2016 hepatitis A outbreak in Canada from frozen fruit is only one of several similar outbreaks that have occurred in the past in different industrialized countries. Hepatitis A is spread through the faecal-oral route, and although it is more common in less developed nations where poor sanitation conditions are prevalent, improper hygiene during food handling can cause an outbreak. Identifying the specific molecular subtype of hepatitis A can help trace which cases are associated with a particular outbreak. It is recommended that anyone handling food take proper precautions in food safety in order to prevent further hepatitis A outbreaks. If worried, one should obtain a pre-exposure vaccination to acquire permanent immunity to the virus.
- Chironna M, Lopalco P, Prato R, Germinario C, Barbuti S, Quarto M. J Clin Microbiol. 2004;42(6):2825-8. http://dx.doi.org/10.1128/JCM.42.6.2825-2828.2004
- Swinkles, H. M. Et al (2014, May 8). Hepatitis A Outbreak in British Columbia, Canada: The Roles of Established Surveillance, Consumer Loyalty Cards and Collaboration, February to May 2012. Eurosurveillance, 19(18), 20792. http://dx.doi.org/10.2807/1560-7917.ES2014.19.18.20792
- Hutin YJ, Pool V, Cramer EH, Nainan OV, Weth J, Williams IT, et al. A multistate outbreak of hepatitis A. National hepatitis A investigation team. N Engl J Med. 1999;340(8):595-602.
- Gillesberg Lassen S, Soborg B, Midgley SE, Steens A, Vold L, Stene-Johansen K, et al. Ongoing multi-strain food-borne hepatitis A outbreak with frozen berries as suspected vehicle: four Nordic countries affected, October 2012 to April 2013. Euro Surveill. 2013;18(17):pii=20467.
- Nordic outbreak investigation team. Joint analysis by the Nordic countries of a hepatitis A outbreak, October 2012 to June 2013: frozen strawberries suspected. Euro Surveill. 2013;18(27):pii=20520.
- Heymann DL. Hepatitis, viral. In: Control of communicable diseases manual. 19th ed. Washington, DC: American Public Health Association; 2008. p. 278-84.
- Victor, J. C., PhD, MPH. Et al (2007, October 25). Hepatitis A Vaccine versus Immune Globulin for Postexposure Prophylaxis. The New England Journal of Medicine,357, 1685-1694. doi:10.1056/NEJMoa070546